Rh incompatibility is a condition that develops when an Rh negative mother is carrying an Rh positive infant in her womb. This is also called as an Rh-induced hemolytic disease of the newborn. During pregnancy, the red blood cells of the unborn baby can cross into the mother's bloodstream thru the placenta. As an Rh negative mother, they treat these circulating red blood cells of the baby as a foreign matter and produces antibodies towards it. These anti-Rh antibodies then circulates back into the bloodstream and crosses back into the placenta attacking the developing baby's red blood cells. Bilirubin is the by-product when red blood cells are broken down. This causes the infant to become yellow or jaundiced. The levels of bilirubin in the baby's blood may range from mildly elevated to severely high.
Because it takes time for antibodies to get developed, first-born infants are ussually not affected. However, if the mom has previous miscarriages or abortions that has sensitized her immune system, then increases the chance of the first-born to get affected. One has to remember that Rh incompatibility only occurs to Rh negative mothers carrying Rh positive infants. Thanks to commercially manufactured immunoglobulins, called RhoGAM, these problems are getting very uncommon in countries which practiced good pre-natal care. Symptoms of Rh incompatibility ranges from its mildest forms to the deadliest. In its mildest form, Rh incompatibility causes destruction of red blood cells in infants, wherein, infants after birth will manifest yellowing of the skin and whites of the eyes, poor muscle tone and lethargy.
Before delivery, the mother may have an increased amount of amniotic fluid around her unborn baby.
There may be:
- A positive direct Coomb's test result
- Higher-than-normal levels of bilirubin in the baby's umbilical cord blood
- Signs of red blood cell destruction in the infant's blood
Because Rh incompatibility is preventable with the use of RhoGAM, prevention remains as the best treatment. Treatment of an infant who is already affected depends on the severity of the condition.
Infants with mild Rh incompatibility may be treated with either feeding and fluids (hydration) and phototherapy using bili-lights.
Full recovery is expected for mild Rh incompatibility. Possible complications include: brain damage due to increased levels of bilirubin, fluid build-up and swelling of the baby and problems with mental function, movement, hearing, speech and seizures.
Rh incompatibility is almost completely preventable. Rh-negative mothers should be followed closely by their obstetricians during pregnancy. Special immune globulins, called RhoGAM, are now used to prevent Rh incompatibility in mothers who are Rh-negative. If the father of the infant is Rh-positive or if his blood type cannot be confirmed, the mother is given an injection of RhoGAM during the second trimester. If the baby is Rh-positive, the mother will get a second injection within a few days after delivery. These injections prevent the development of antibodies against Rh-positive blood. However, women with Rh-negative blood type must receive injections: during every pregnancy, if they have had miscarriages or abortions, after prenatal tests such as an amniocentesis and chorionic villus biopsy and after an injury of the abdomen during pregnancy.
I hope this will serve as a helpful learning tool for pregnant women who are known to have an Rh negative blood type.
Stoll BJ. Blood disorders. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 103.